Method of making paperboard boxes



.Labombarde seeks to solve the problem by United States P t O 2,813,464 METHOD OF MAKING PAPERBOARD BOXES Leon E. La Bombard, Nashua, N. H., assignor, by mesne assignments, to The International Paper Box Machine Company, Nashua, N. H., a corporation of New Hampshire Application March 29, 1954, Serial No. 419,127

13 Claims. (Cl. 9336) This invention relates to a new method of makingpaper boxes and especially those known in the trade as sh1pp1ng containers made from corrugated or fibre board.

The demand for boxes or cartons made at low cost, and used for packaging and shipping, has resulted in numerous highly developed, high speed machines and methods for folding the same from solid paper board of various thicknesses. Such boxes are cut, creased or scored in a flat blank, then folded into the desired shape and then stitched, stapled, glued or stayed together.

Progressive folding, wherein the blanks are fed onto belts by feed mechanism and thereafter are continuously and progressively folded by twist belts without timing of the blanks, is the most rapid way of making tubular shaped containers at high speed. Regardless of the material used in such progressive folding, however, the twist belts first operate on the leading portion of the blanks tending to fold on the inside line of the creases and later operate on the trailing portions of the blanks tending to fold on the outside of the creases, thus creating a tapered or inaccurate, misaligned fold. When the paper board is thin and the creases narrow, such a tapered fold is usu ally commercially acceptable but with soft, thick fibre board, or corrugated paper board, the taper is so pronounced as to create a commercially unacceptable product. The degree of such tapered or misaligned folding is dependent therefore on the consistency and strength of the stock, the width of the crease necessary to prevent breaking or cracking of the stock and the length of the crease line upon which the fold takes place with relation to the dimensions of the panel being folded. There are thus certain sizes and shapes of blanks which prove diflicult to fold accurately and especially difficult when formed of weak thick stock as corrugated paper board.

When the attempt has been made to fill the increasing demand for corrugated paper boxes by modifying machinery formerly used for folding solid paper board boxes or by designing new machinery for the purpose, considerable trouble has been encountered. The fluting of the corrugated paper board usually runs in the direction of the crease lines upon which a fold is desired and if the flutes do not exactly register with the crease line, or if the adherence of the flutes to the liner is non-uniform, the resulting fold is often out of line. In addition the flutes of the corrugated paper tend to yield under the pressure of the pressure rolls which form the creases and to then spring back, thus tending to erase the crease and to permit a misaligned flute to become the fold line.

The problem of folding corrugated paper boxes from a cut and scored blank is noted in U. S. Patent No. 1,534,007 to H. S. Labombarde of April 14, 1925, the foldng in this patent being accomplished by folder bars and twist belts and any misfolded cartons being straightened by the resistance of the nip of a pair of rolls In U. S. 1925, H. S. the use of six to accomplish Patent No. 1,565,167 of December 8,

twist .belts plus a traveling set of thin plates "ice to'square up any misfolded cartons after folding. In U. S. Patent No. 2,284,792 of June 2, 1942 to N. A. Anderson, pivoted pusher feet are used to push on the trailing edges of a folded blank against the resistance of a stop member also for the purpose of squaring up any misfolded cartons. A. F. Shields in U. S. Patent No. 2,336,507 of December 14, 1943 provides oppositely disposed lines of rollers along the path of the folded crease lines of a blank to true up the fold by resetting the crease. A. W. Werner in U. S. Patent No. 2,379,127 of June 26, 1945 seeks to secure a true fold by the use of a plurality of twist chains together with a travelling pressure element applied to the inside of the crease and special pre-creasing rollers. F. J. Spiess in U. S. Patent No. 2,637,251 of May 5, 1953 provides rolls of the Werner type but with circumferential grooves to crush or soften the folded crease line, thereby squaring up the fold of any misaligned cartons.

It is to be noted that the above mentioned patentees and others have all recognized that the high speed folding of corrugated box blanks often results in inaccurately folded boxes and each patentee has provided mechanism for keeping the folds true during folding or for squaring the-folding together with a plurality of chai a d l afiattened tubular carton and .liner's 20 and ,22 medium 21 and termed up the folds after folding. It should also be noted that in machines and methods for folding paper boxes, not only. from corrugated paper board, but even from solid paper board, as far as I am aware the teaching of the art has been to first slot, crease and score the blanks and then to fold and fasten the blanks into containers.

I have discovered that by departing from this teaching, blanks of corrugated or other paper board can be folded in high speed machines without requiring complicated trueing or squaring mechanisms. It is the principal object of this invention to provide a method for making boxes of paper board especially of corrugated paper, wherein a true fold is assured regardless of the automatic folding machinery used.

A further object of the invention is to provide a method of folding corrugated paper blanks which results in straight parallel folds without the need of complicated flap control mechanisms or squaring up mechanisms.

Another object of the invention is to provide a method of folding paper board boxes without misaligned fold lines even when the boxes are of large area and shallow, such boxes presenting especial folding problems in view of their large panels, but short webs of paper along the lines of Other objects of the invention will be apparent from the specification and drawings in which Fig. 1-illustrates diagrammatically a machine which maybe used for carrying out the method of this invention.

Fig. 2 is a plan view of a sheet of corrugated paper board ready to be formed into a carton blank.

Fig; 3 is a plan view of a flat blank creased and cut in accordance with the method of this invention.

Fig. 4 is a plan view of the blank of Fig. 3 folded into with a glue flap adhered to the adjacent side wall panel.

Fig. 5 illustrates the stacking stage used with glue flap type cartons to assure permanent adhesion of the flap. Fig. 6 illustrates a portion of the final stage of the method of this invention comprising the slotting of the leading closure flaps, and p Fig. 7 also illustrates another portion of the final stage of the method of this invention comprising the slotting of the trailing closure flaps of the carton.

While my method of forming cartons is useful with blanks made of solid paper board, it is especially adapted for folding blanks made of corrugated paper board such as shown at A in Fig. 2. The corrugated paper may be of anywell known type, but usually comprises a pair of adhesively secured to a fluted paper double face in the trade.

The corrugated paper board -A is usually advanced through the various stages of folding in a folding machine in the same direction as the direction of its flutes and it is the folding of-tlie same onlines parallel to the flutes tliat may cause misaligned-folds.

As shown in Fig. 3, the initial step of this invention is the forming of a blank B which differs from blanks prevtou'slyused in the trade. The blank B is cut peripherally to the desired exterior outline, which outline preferably includes a suitable attachmentflap such as 23, in an' 'well known manner and by any suitable machinery. Two spaced apart parall'el'crease lines 24 and ZS are'fOri'r-Ied in blank B running perpendicular to the direction of the flutes 21'as well as at least three spaced apart parallel crease lines '26; 27 and 28 running parallel to the'diree'tion of theflutes. Another crease line "such as 29, parallel to' lines 26, 27 and 28 is formed for eachattachrnent' fia p such as 23 provided. I

Such a blank will form a collapsed box having four end closure panels at each opposite end, which type boat is usedyherein as atypical illustration of the method. To form-a collapsed box of paperboard having closure'p'anels at one endonly, a single crease line such as'24 is" formed laterally of the blank and at least three parallel crease lines such as26, 27 and 28 are formed longitudinallyof the-blank together with a suitable attachment flap"such as23.

For convenience I call crease line 27 the halving crease line, andI call the pair of crease lines 26 and 28 the quartering crease lines. It will be apparent that the blank B is thus divided up into four sidewall panels 30,31, 32 and 33, four end closure panels 34, 35, 36 and37 and four opposite end closure panels 38, 39,40 and '41, plus the glue flap 23. lt'has heretofore been the custom i-n" the trade to cut slots between each pair of adjacent closure panels for example, between panels 34 and 3 5, between panels 38 and 39, etc., thus leaving only the webs ofma- 'terial between each pair of adjacent side wall panelsas the line of articulation for folding. Carton blanks'so creased and slotted thus have beendifficult tofold on a true quartering line, because the web ofmaterial between the adjacent side panels has been so short relative to the area of the closure panels that the foldbecame easily distorted and'misaligned.

It is the essence of this invention'that'nocrease line upon'whicha fold is to take place in forming the'car'ton is" slotted and thatall such crease lines are intact and'extend from one edge such as 42 to the opposite edge'sufch as 43 of the blank. Since a fold does not take place along the-"halving crease line 27 in formin a flattened tubular carton from blank B, I prefer to form a slot 45 between the median closure panels 35 and 36 and a similar slot 46 between the median closure panels 39 and 40' as part of the initial step of forming the blank B.

The next step or stage of my method'is the folding over of side panel 30, togetherwith its articulated closure panels 34 and 38 on the intact, unslotted, "quart'ering icrease line 26 to overlie flatwise the adjacent panels 35,

31 and' 39. Since 'the attachment flap 23 is on side panel 33, and is desired to be on the outside of the carton, the sidepanel 33 and its articulated closure panels 37 and 41 'a're' folded on the intactunslotted quartering' crease line 28 slightly subsequent to the above mentioned folding, "whereby they will overlie fiatwise' on the adjacent panels 36. 32 and 40. Because the creaselines'26 and 28ext'end thefull distance between edge '42 andedge43 of blank B, rather than being merely a narrow'web between the adjacent side panels, the effect of the originafcreasingis more pronounced and the fold tends to follow the crease rather than a misaligned flute. Similarly, since'flhe closure fiaps'have not been freed by slots to become independent Yflaps, off centre pressure from folding elements'of a folding'machine is resisted by theweb connecting adjacent closure panels and especially by the intact outer liner whereby thefold tends to be true.

Preferably, the open corner of the carton is closed immediately after the folding step by stays or gummed tape or by the securing of an overlapping flap such as 23 to the side panel such as 30. Where a glue flap 23 is used, adhesive is applied to one surface thereof in a well known manner prior to folding in order that it will adhere to the side-panel 30 as soon as it contacts the same. The flattened tubular carton thus'formed from blank B is designated C in Fig. 4 and it should be noted that outer closure panels 34, 37, 38 and 41 are still-unsevered from the respective median closure panels 35, 36, 39 and .41.

When a glue flap type of carton such as C is formed by my method, I prefer to introduce a stacking or shingling step immediately after the folding step as indicated in Fig. 5. The cartons C thus pile up one upon the other, thereby slowing their rate of advance and providing a time period in which the glue may set before the cartons reach the final slotting step. By so permitting the glue to firmly adhere, the carton thereafter resists any possibility of becoming distorted from the pressure of the slotting or severing knives.

The finalstep or stage of the method of this invention is shown in Fig. 6 and Fig. 7 wherein a flattened tubular carton, permanently connected at all four corners of its sidewalls, is finally severed to free its closure flaps. Preferably a slot 50 is formed to sever the connecting web between closure panels 33 and 39 simultaneously with the formation of a slot 51 severing the connecting web between closure panels 40 and 41. Thus panels 38, '39,'40 and 41, all on the same side of the side wall panels, become independent closure flaps articulated only along crease line 25 of a carton designated D.

The'reafter,-a slot 52 is formed to sever the connecting web between closure panels 34 and 35 simultaneously with the forming of a slot 53 to sever the connecting web between-closure panels 36 and 37. Closure panels 34, 35, 36 and 37 thus become closure flaps articulated "only along line 24 and the carton E represents the desired carton formed by the method of this invention.

"As-shown diagrammatically in Fig. 1, a machine by which my method may be used is designated F and includes conveyor chains or belts 70 and 71, separated by a'convey'or chain or belt 72, both of a type well known in the art for advancing blanks along the paper line 'of a machine. A stack 73 of flat individual sheets such as A, held in a magazine 74 of any well known type may be provided, whereby the spaced lugs 75 on chain-70 or any suitable feed mechanism, will draw off the lowermost sheet A in the stack individually and 'succ'essively and advance the same to the creasing and slotting members 76' and 77.

The members 76 and 77 are illustrated as a pair of rolls onehaving' raised elements such as 78 on its surface, 'and'the other having complementary recesses such as79 on its surfacecap'able of impressing creases such as 24, :25, 26, 27, 28 and '29, cutting slits or slots such as 45 and'46 and cutting flaps such as 23 in a sheet A. It will be'apparent that the material of blanks B could be delivered to the creasing and slotting mechanism in continuous web form rather than in individual sheets and that the creases, slots and cutouts of the blanks B could be applied by other means well known in the trade. The lugs 75 of chain 70 advance the blanks B past folding mechanism shown diagrammatically as a pair of twist belts such as80, whereby the panels 30, 34 and 38 are first infolded and then the panels 37, 33 and 41 are infolded, asindicated in dotted lines, to form flattened tubu- "lar cartons such as C. If the carton is a glue flap type, the conveyor 72 may be operated at a slower speed than conveyor-70 causing the cartons C, delivered theretoby conveyor 70 to pileup in a shingled stack 83 while the glueor adhesive becomes permanently set.

Spaced 'lugs'84 on conveyor 71 individually and successively pick up the lowermost carton C from the stack 83 and advance the same first past disc type slitting 5 knives such as 81 and then past disc type slitting knives such as 82. Knives 81 form the slots 50 and 51 forming the carton designated D and knives 82' form the slots 52 and 53 of the final carton E. l

As shown in Figs. 6 and 7 I prefer to form slots 50, 51, 52 and 53 parallel to the direction of the flutes as at 90 but curved outwardly near the base of the slot as at 91. The outer liner 20 is thus cut more deeply. than the inner liner 22 and upon closing the flaps the excess material caused by the curved cut tends to seal the corner of the carton making that corner sift proof. By slotting the closure panels such as 34 and 35 after they have been folded to overlie each other, a curved slot of the desired configuration is easier to obtain thanwhen the blank is still flat. In addition the making of a curved slot between closure panels when the blank is flat results in a pointed apex at the base of the slot which is likely to fracture further upon foldinglof the panels and make an imperfect carton.

The method of this invention can be applied to existing machines for making printed or unprinted blanks by eliminating the knife elements therefrom which sever the closure panels from each other and installing similar knife elements for severing such closure panels into separate flaps after the tubular box or carton has been folded and formed.

Where additional sift proof corners are desired, I not only do not sever the longitudinally extending crease lines 26 and 28 between each median closure panel 35, 39, 36 or 40 and its adjacent outer end closure panel 34, 38, 37 or 4-1, but I also do not sever the longitudinally extending crease line 27 between each pair of median closure panels 35 and 36 and 39 and 40. In addition, I elongate the flap 23 whereby it extends along part, or all, of the side edges of the closure panels 37 and 41. The blanks so cut and creased are then folded into a flattened tube such as at C and the quartering crease lines 27 and 28 are severed with a curved cut as at D and E. The flattened tube is then opened lip-and refolded by any well known mechanism to present the halving crease line 27 and the attachment flap crease line 29 on each opposite side edge, whereupon the median closure panels are severed into flaps and the end closure panels are severed into flaps in the same manner as illustrated in Figs. 6 and 7.

It should be noted that a blank which forms a box having end closure panels at one end only may also have its quartering crease lines severed by a single set of knives after folding and then be refolded whereby the alternate crease lines are severed by a second set of knives. In addition it should also be noted that with boxes having closures at both ends a single rotating knife support may have two cutting segments, the first segment severing leading end closure panels and the second segment severing trailing end closure panels.

I claim:

1. The method of folding a tubular carton from a flat blank of paper board which consists in initially creasing a flat, unfolded blank with at least one crease line laterally of the blank, a halving crease line longitudinally of the blank and a pair of quartering crease lines longitudinally of the blank to form four articulated side wall panels, each with an end closure panel articulated thereto and initially severing only that portion of said halving crease line located between each two adjacent median end closure panels leaving each said quartering crease line intact and unsevered; then moving said blank in a longitudinal direction along a path while folding each outer side wall panel, together with the end closure panel articulated thereto on an intact and unsevered quartering crease line to overlie the adjacent median side wall panel and end closure panel and then continuing to move said blank along said path while severing each of said quartering crease lines between each median closure panel and the outer end closure panel folded thereover to separate the same into independent end closure flaps.

2. A method as specified in claim 1 wherein two parallel lateral crease lines are formed in said blank and the final step of severing said quartering crease lines is accomplished first on the closure panels articulated at one lateral crease line of the side panels and then on the closure panels articulated at the other lateral crease line of the side panels.

3. A method as specified in claim 1 plus the step of connecting the free edges of said side wall panels to form a closed articulated corner of a flattened tubular carton immediately after said folding step, immediately before the final step of severing said quartering crease lines and while said carton is continuously moving along said path.

4. A method as specified in claim 1 plus the steps of adhesively connecting said overfolded outer side wall panels to form a closed, articulated corner on the flattened tubular carton formed by so folding said blank immediately after the folding step, then stacking a plurality of other flattened tubular cartons formed thereafter on said carton to apply weight thereon and then withdrawing said carton from under said stack, all prior to the final severing of said quartering crease lines and while said carton is continuously moving along said path.

5. The method of fabricating a tubular carton from a flat sheet of paper board which consists in first forming a flat, unfolded blank with the panels and flaps therein defined by crease lines and with slots only on lines upon which no fold is required to form a flattened tube therefrom; then continuously moving said blank along a path while folding said blank into a flattened tube on said unslotted crease lines only and while finally slotting said flattened tube along said previously unslotted lines to separate the required panels into independent flaps.

6. The method of making squared-up tubular cartons from corrugated paper board which comprises the steps of continuously moving a flat, creased, unfolded blank longitudinally while first folding the panels thereof into a flattened tube on intact longitudinal crease lines which have not been severed and which extend from one lateral edge of the blank to the opposite lateral edge in the direction of the flutes of said board; then joining the free longitudinal edges of said flattened tube to form a closed flattened carton and finally severing the intact longitudinal crease lines of said carton inwardly from a lateral edge thereof to form independent end closure flaps therein each articulated to a side wall panel.

7. A method as specified in claim 6 wherein said final severing is in a direction parallel to the flutes except adjacent the base of the line of severance, the base portion of said line of severance extending outwardly in a curve from the inner liner to the outer liner of the corrugated paper board to form sift-proof corners on said carton.

8. The method of fabricating a shipping container from a flat sheet of paper board which consists in first creasing said sheet with a lateral crease line, to divide said sheet into a side panel section and an end closure panel section, and with a plurality of longitudinal crease lines to divide said sections into individual side panels and end closure panels, then moving said sheet along a path in projection of said longitudinal crease lines while folding said sheet along two of said longitudinal crease lines to form a flattened tube and then continuing to move said sheet along said path while severing each longitudinal crease line from the lateral edge of said end closure panel section to said lateral crease line to form end closure flaps on said container.

9. A method of fabricating a sift-proof shipping container from a flat blank of paper board which consists in first creasing said sheet with two lateral and four longitudinal crease lines to define four side wall panels, each with an upper and lower end closure panel attached thereto and to define an attachment flap coextensive with a side panel and with an adjacent portion of the upper and lower end closure panels attached to said side panel, then folding said blank along a first pair of alternate longittidinal crease lines to form a flattened unclosed tube, then joinings'aidattachment flap to the opposite edge portion 'of-said blank to close said tube; then severing said first pair-of alternate longitudinal crease lines, uponwhich said'tube was folded, with lines of severance which-extend longitudinallyfrorn the lateral edges of the tube to proximate the lateral crease lines and then curve-outwardly thereby'separating the adjacent upper and adjacent lower end closure panels; then erecting and refolding said flattened tube along the second pair of alternate longitudinal crease lines to again form a flattened closed tube and then severing said second pair of alternate longitudinalcrease lines, upon which said tube was refolded, with lines of severance which extend longitudinally from the lateraledges of the tube to proximate thelateral crease lines thereof and then curve outwardly thereby separating theadjacent upper and adjacent lower end closure panels.

1 0. The method of making a shipping container of paper board of the type having four side walls attached to each other and end flaps foldably connected to said side Walls-to form end closures, said method consisting in first forming a blank with side wall panels and end closure panels defined therein only by crease lines; then moving'said blank along a path while folding said blank along certain of said crease lines to form a flat, incomplete tube and joining the adjacent free side edges thereof to'complete the tube and then continuing to move said tube along said path while severing said tube along said fold lines to convert said end closure panels into end closure flaps.

11.-The method of making a flat tubular carton of paperboard from a flat unfolded sheet which comprises forming at least one lateral crease line and three spaced apart longitudinal crease lines in said flat unfolded sheet to define four side wall panels longitudinally hinged to each other and at least four end closure panels each laterally hinged to a side Wall panel along said lateral crease line; feeding'said flat sheet along a path while folding the outer side Wall panels and outer end closure panels on the outer longitudinal crease lines to overlie flatwise the inner side wall panels and inner end closure panels; :continuing to teed said-folded sheet alongrsaid pathwhilepermanently connecting the free outer .edges of"said=-outer :side wallpanels to forma flat'tube and continuing to feed said flat tube alongvsaid path while severing theend: closure panelsthereoffrom each other along the "portion of saidlongitudinal crease lines initially joining. the 1 same.

12. "T he method of making squared-up tubular cartons from :corrugated paperboard which comprises the steps of first folding theupanels :of a creased blank into a'flattenedtube on intactcrease lines which have not been severed and 'whichaextend. from one edge of the blank to the opposite edge in therdirection of the flutes of said board; then joining the free 'edgesof said flattenedtube to" form-1a.closed flattenedcarton' and finally severing the intact crease lines of said carton in a direction parallel tothe"flutes except :adjacent the base of the line of severance, :-the base portion ofsaid line of severance extending outwardly in a curve from the inner liner to the outerzlinersof saidboard to form sift proof corners on saidrcarton andusaid lines of severance forming independent, .articulated end closure flaps on said carton.

13. aTheamethod of making a. container of paperboard of the type having four side walls attached to each other and end flapsfoldably connected to said side walls to form an end closure, said method consisting in first formingta flat unfolded blank with the side wall panels .andtend closure panels defined by crease lines and the end'closure,panels separated from each other by lines of severance onlymonzlines upon which no fold is required toforrnaaflattened tube from said blank; then moving saidablank alongapath while folding said blank on said unsevered crease .lines and joiningthe edges thereof to form a flattened tube and finally. severing said unsevered crease lines tocornplete the separation of said end closure panels into. end closure, flaps.

Gruenberg Sept. 13, 1932 Spiess May 5, 1953 

